An allergy reaction is referred to as an immediate-type or a type-I hypersensitive reaction and is mediated by an IgE antibody. When a living body is exposed to an allergen for the first time, an IgE-antibody-producing B cell starts producing a soluble IgE molecule. The soluble IgE molecule binds to a high-affinity IgE receptor present on a surface of mast cells or a basophils. If the living body encounters the same allergen again, the high-affinity IgE receptor is crosslinked with the IgE antibody by the allergen, causing the allergy reaction in which histamine and cytokine are released from a cell.
Anti-IgE antibodies that neutralize IgE antibodies are put into practical use as antibodies for suppressing the allergy reaction. However, a human IgE antibody that binds to the high-affinity IgE receptor has a property of activating mast cells and basophils solely or in combination with the allergen further binding thereto. Therefore, in general, the human IgE antibody is not considered to be useful for neutralization of the allergen.
On the other hand, manufacturing of a human antibody is no longer a difficult technique and a human antibody can be prepared with various methods (e.g., an Epstein-Barr virus (EBV) immortalization method, a phage display method, and a complete human antibody producing hybridoma method).
Human IgE monoclonal antibodies are also reported as being manufactured by using a phage display method, for example (Patent Document 1, Non-Patent Literature 1).